diff --git a/insns.def b/insns.def
index 629a2f1bc9..132ce2f179 100644
--- a/insns.def
+++ b/insns.def
@@ -44,9 +44,11 @@
          `insn_stack_increase`.
 
        * handles_sp: If it is true, VM deals with sp in the insn.
+         Default is if the instruction takes ISEQ operand or not.
 
        * leaf: indicates that the instruction is "leaf" i.e. it does
-         not introduce new stack frame on top of it.  Default true.
+         not introduce new stack frame on top of it.
+         If an instruction handles sp, that can never be a leaf.
 
    - Attributes can access operands, but not stack (push/pop) variables.
 
@@ -357,7 +359,7 @@ putiseq
 (ISEQ iseq)
 ()
 (VALUE ret)
-// attr bool leaf = true; /* yes it is */
+// attr bool handles_sp = false; /* of course it doesn't */
 {
     ret = (VALUE)iseq;
 }
@@ -713,7 +715,6 @@ defineclass
 (ID id, ISEQ class_iseq, rb_num_t flags)
 (VALUE cbase, VALUE super)
 (VALUE val)
-// attr bool handles_sp = true;
 {
     VALUE klass = vm_find_or_create_class_by_id(id, flags, cbase, super);
 
@@ -740,7 +741,6 @@ send
 (CALL_INFO ci, CALL_CACHE cc, ISEQ blockiseq)
 (...)
 (VALUE val)
-// attr bool handles_sp = true;
 // attr rb_snum_t sp_inc = - (int)(ci->orig_argc + ((ci->flag & VM_CALL_ARGS_BLOCKARG) ? 1 : 0));
 {
     struct rb_calling_info calling;
@@ -757,7 +757,6 @@ opt_send_without_block
 (CALL_INFO ci, CALL_CACHE cc)
 (...)
 (VALUE val)
-// attr bool leaf = false; /* Of course it isn't. */
 // attr bool handles_sp = true;
 // attr rb_snum_t sp_inc = -ci->orig_argc;
 {
@@ -828,7 +827,6 @@ invokesuper
 (CALL_INFO ci, CALL_CACHE cc, ISEQ blockiseq)
 (...)
 (VALUE val)
-// attr bool handles_sp = true;
 // attr rb_snum_t sp_inc = - (int)(ci->orig_argc + ((ci->flag & VM_CALL_ARGS_BLOCKARG) ? 1 : 0));
 {
     struct rb_calling_info calling;
@@ -845,7 +843,6 @@ invokeblock
 (CALL_INFO ci)
 (...)
 (VALUE val)
-// attr bool leaf = false; /* Of course it isn't. */
 // attr bool handles_sp = true;
 // attr rb_snum_t sp_inc = 1 - ci->orig_argc;
 {
diff --git a/tool/ruby_vm/models/bare_instructions.rb b/tool/ruby_vm/models/bare_instructions.rb
index 7d9ed6da5a..2767f383e6 100755
--- a/tool/ruby_vm/models/bare_instructions.rb
+++ b/tool/ruby_vm/models/bare_instructions.rb
@@ -144,6 +144,7 @@ class RubyVM::BareInstructions
   end
 
   def predefine_attributes
+    # Beware: order matters here because some attribute depends another.
     generate_attribute 'const char*', 'name', "insn_name(#{bin})"
     generate_attribute 'enum ruby_vminsn_type', 'bin', bin
     generate_attribute 'rb_num_t', 'open', opes.size
@@ -151,11 +152,24 @@ class RubyVM::BareInstructions
     generate_attribute 'rb_num_t', 'retn', rets.size
     generate_attribute 'rb_num_t', 'width', width
     generate_attribute 'rb_snum_t', 'sp_inc', rets.size - pops.size
-    generate_attribute 'bool', 'handles_sp', false
-    generate_attribute 'bool', 'leaf', opes.all? {|o|
-      # Insn with ISEQ should yield it; can never be a leaf.
-      o[:type] != 'ISEQ'
-    }
+    generate_attribute 'bool', 'handles_sp', default_definition_of_handles_sp
+    generate_attribute 'bool', 'leaf', default_definition_of_leaf
+  end
+
+  def default_definition_of_handles_sp
+    # Insn with ISEQ should yield it; can handle sp.
+    return opes.any? {|o| o[:type] == 'ISEQ' }
+  end
+
+  def default_definition_of_leaf
+    # Insn that handles SP can never be a leaf.
+    if not has_attribute? 'handles_sp' then
+      return ! default_definition_of_handles_sp
+    elsif handles_sp? then
+      return "! #{call_attribute 'handles_sp'}"
+    else
+      return true
+    end
   end
 
   def typesplit a